Probabilistic transmission planning in England and Wales

Following the changes in institutional arrangements in England and Wales, there is no centrally co-ordinated planning of new generation or closure of existing generation. New generation enters into a contract with the transmission company for connection. This contract will describe the project in sufficient detail to enable the appropriate transmission capacity to be determined. The decision to proceed with the generation project rests with the generation company, of which there are now thirty two. As new generation enters the market, an alike amount of generation is likely to leave the system with little advance notice. The paper examines the forecasting of future generation backgrounds and the techniques used to identify the range of transmission capacity that would be required to cope with the resulting power flows. The paper shows that planning future transmission capacity is an exercise in risk management and identifies a portfolio of measures the facilitates trading and competition in the energy pool and at the same time optimises the value of the transmission service.